CN104029562B - Compact type pulse vacuum rotary shaft hub lock - Google Patents

Abstract

A pulse vacuum hub lock system for selectively engaging a hub to a half shaft includes a chuck housing assembly received in a bore in the hub. The chuck housing assembly supports a clutch ring for movable engagement between splines in the hub and directly on the axle shaft. A diaphragm is connected to the piston assembly and activates the piston assembly to engage or disengage a latching mechanism that secures the clutch ring in an engaged or disengaged position in response to vacuum pressure. A piston spring and an auxiliary spring are disposed between the primary and secondary pistons of the piston assembly and allow separation in the vacuum required to activate the latching mechanism. The vacuum hutch system is compact to seat inside an opening in the outer surface of a rim.

Description

Compact pulse Vacuum gyroaxis hublock

Cross-Reference to Related Applications

This application claims the rights and interests of the U.S. Provisional Application No.61/774,169 submitted on March 7th, 2013.Above-mentioned application Overall disclosure include in herein by reference.Technical field

Present disclosure relates to the locking hub system of a kind of vehicle, systems a kind of group with minimizing The locking hub chuck that the pulse Vacuum of dress length starts.

Background technology

This part provides the background information relevant to present disclosure, and this background information not necessarily constitutes existing skill Art.

In the commonly provided four wheels of vehicle that be designed to highway and cross-country use, that there is four-wheel drive ability two Optional joint/the disengaging of wheel.Wheel to be departed from necessarily possesses the power drive system in following automotive power, its In highway used and in order to avoid the unnecessary energy expenditure of power driving module of off working state and abrasion, it is provided that Hublock is so that wheel shaft separates with the wheel of vehicle.Original hublock equipment is for manually booting.Driver/operator can be by car Stopping, engage transfer case and disconnect system, the driver plate during then hand rotation is positioned at each wheel hub makes to activate hublock Wheel separates with wheel shaft.

Subsequently, develop and automatically activate wheel hub lockwork.Automatically the locking wheel hub of four-wheel drive vehicle is currently available for perhaps The most different design configurations.These configurations include that direct manual clutch engages, long-range vacuum operated clutch engages and remote pressure Clutch engages.The system of Previous designs includes the somewhat complex design needing to relate to many parts, and these parts make equipment produce Costliness and/or assembling complexity.Present disclosure provides a kind of greater compactness of component package, to be more easily assembled to vehicle and more Add attractive in appearance.

Summary of the invention

This part provides the comprehensive public of the overall summary of present disclosure rather than its full breadth or its all features Open.

Present disclosure provides a kind of compact pulse Vacuum gyroaxis hublock, and it provides chuck to set for the ease of assembling Meter.Hublock includes the clutch ring with multiple rows of soldered tooth, and the external splines on constant shaft reduces what clutch ring moved axially Amount.Hublock utilizes pulse Vacuum joint method, and it allows limited use vacuum, therefore allows the vacuum system of vehicle to have ratio The endurance cycles that continuous vacuum hublock is lower.

Hublock also uses two springs for pulse Vacuum joint/detachment system.Bigger omnidistance spring is used for In the whole stroke of main piston, diaphragm provides retroaction to described main piston.Second spring for by need bigger vacuum with Compression main piston completely helps to reduce the whole stroke of main piston.The system of two springs allows sensitizing pulse/block sytem institute The bigger separation of vacuum needed.This allows bigger system tolerance, therefore makes it more sane, but allows less axial simultaneously Stack size.

The combination of present disclosure allows the axially stacked, so that the present invention's is designed to the most intensive envelope of minimum Dress.This allows for traditional automatic outboard wheel end to disconnect wheel with the original equipment manufacturer being entirely encapsulated in traditional style After central cover.

The suitability in other field will become apparent from description provided herein.Description in present invention and The purpose that instantiation is merely to illustrate, and be not limited to scope of the present disclosure.

Accompanying drawing explanation

Accompanying drawing described herein only for selected embodiment rather than the illustrative purpose of all possible enforcement, and And be not limited to scope of the present disclosure.

Fig. 1 is the cross section of the hublock mechanism of the vacuum startup being applied to rotating shaft of the principle according to present disclosure Figure；

Fig. 2 is the decomposition of the assembly of the wheel hub clutch lock of the pulse Vacuum startup illustrating the principle according to present disclosure Axonometric chart；

Fig. 3 is the axonometric chart of the hublock mechanism of the pulse Vacuum startup illustrating the principle according to present disclosure；

Fig. 4 is the detailed cross-sectional view of the hublock mechanism of the pulse Vacuum startup of the principle according to the present invention, it is shown that This hublock mechanism is in disengaging configuration；

Fig. 5 is the detailed of the hublock mechanism of the pulse Vacuum startup of the principle according to the present invention

Cross-sectional view, it is shown that this hublock mechanism is in bonding station；

Fig. 6 is the partial sectional view of the joint illustrating blocking mechanism；And

Fig. 7 is the detailed progress figure of joint and the disengaging illustrating blocking mechanism.

In several views of whole accompanying drawing, corresponding reference number indicates corresponding part.

Detailed description of the invention

It is described more fully with exemplary now with reference to accompanying drawing.

There is provided exemplary so that present disclosure is more thorough, and scope is fully conveyed to this area Technical staff.The many details (such as, the example of concrete assembly, equipment and method) of statement are to provide present disclosure The thorough explanation of embodiment.It will be apparent to those skilled in the art that: be required for detail, exemplary Embodiment can be implemented by many different forms, and exemplary also should not be construed as in the restriction disclosure The scope held.In some example embodiments, well-known process, well-known device structure it are not described in detail And widely-known technique.

Terms used herein is only for describing the purpose of particular exemplary embodiment, and is not limited to.Herein Singulative " one " used and " described " may also be used for including plural form, unless the context clearly indicates otherwise.Term " comprise ", " including " and " having " is inclusive, therefore specifies described feature, integer, step, operation, element and/or assembly Existence, but be not excluded for the existence of one or more further feature, integer, step, operation, element, assembly and/or a combination thereof Or add.Method described herein step, process and operation be not interpreted as inevitable requirement with the particular order discussing or illustrate Perform, unless specifically determined execution sequence.It will also be appreciated that and can use step that is extra or that substitute.

When element or layer be referred to as another element or layer " on ", " being joined to ", " being connected to " or " being coupled to " another yuan When part or layer, its can directly on another element or layer, directly engage, be connected or coupled to another element or layer, or can Intermediary element or layer can be there is.On the contrary, when element be referred to as " directly " another element or layer " on ", " being directly joined to ", " straight Receive in succession " or " being directly coupled to " another element or during layer, intermediary element or layer may not be there is.For describing these elements Between other wording of relation can explain by similar mode (such as, exist ... between " for " and directly exist ... it Between ", adjacent " for " direct neighbor " etc.).Term "and/or" used herein includes relevant list in project one or many Any and all of combination in individual.

Although term first, second, third, etc. may be used in this article describing various element, assembly, region, layer and/ Or part, but these elements, assembly, region, layer and/or part should be not limited by these terms.These terms can only be used In an element, assembly, region, layer or part are distinguished with another region, layer or part.Term as " first ", second " and Other umerical term does not indicates that order or sequence as use alpha nerein, unless explicitly pointed out by context.Cause This, the first element discussed below, the first assembly, first area, ground floor or Part I can be referred to as the second element, Two assemblies, second area, the second layer or Part II, without deviating from the teaching of exemplary.

For the ease of describing, can with the relative term in space used herein such as " internal ", " outside ", " ... Under ", " in ... lower section ", " bottom ", " in ... top ", " top " etc., with to shown in figure a element or Feature is described with the relation of other element or feature.The relative term in space can be intended to equipment except institute in figure Show the different orientation in use or operation outside direction.Such as, if the equipment in figure is overturn, then be described as The element of " below other element or feature " or " under other element or feature " will thus be oriented to " at other element Or above feature ".Therefore, exemplary term " in ... lower section " can contain " in ... top " and " ... under Just " the orientation of the two.Equipment can otherwise orient (90-degree rotation or rotate to other direction), and used herein The relative descriptor in space is correspondingly explained.

With reference to Fig. 1, it is shown that hub assembly 10, it pulse Vacuum hublock system including wheel 14 is coupled to semiaxis 16 12.Wheel rim 14 is fixedly secured to wheel hub 18, and wheel hub 18 is pivotally supported on semiaxis 16.It should be understood that wheel shaft 16 He Wheel hub 18 can be coupled to each other by pulse Vacuum hublock system 12 or separately.Vacuum source (not shown) is with as is generally known in the art Mode be connected to pulse Vacuum hublock system 12.

Wheel hub 18 is supported by knuckle 20.Bearing assembly 22 is placed between knuckle 20 and wheel hub 18.Wheel hub 18 includes Medial end 24, medial end 24 include being placed against bearing assembly 22 roll forming fixed system 26(as shown in the figure), Or alternatively, roll forming fixed system 26 can be replaced with bearing adjusting nut.Bearing assembly 22 includes having to extension The outer ring portion 28 of the flange portion 28A stretched, flange portion 28A is fastened to knuckle 20 by securing member 30.

Wheel hub 18 includes that the flange portion 32 radially extended, brake disc 33 and wheel rim 14 are fastened to flange by securing member 35 Part 32.Wheel hub 18 includes extending through hole 38 therein, and it is for being accommodated in semiaxis 16 wherein.Hole 38 includes having interior flower The Outboard Sections 40 of key 42, as best shown in Fig. 4 and Fig. 5.As it is shown in figure 1, needle bearing assembly 44 provides the inner side in hole 38 End, between semiaxis 16 and wheel hub 18.As shown in Figure 4 and Figure 5, hole 38 includes shoulder 48 and groove 50, and groove 50 receives clasp 52, clasp 52 adjoins bearing assembly 54.Bearing assembly 54 adjoins the shoulder 56 of semiaxis 16 to be fixed in the bore 38 by semiaxis 16.Half Axle 16 includes external splines 58A, 58B that two rows on its outboard end are axially spaced.As it is shown in figure 1, knuckle vacuum seal 59 provide between knuckle 20 and semiaxis 16.

As shown in Figure 4 and Figure 5, pulse Vacuum hublock system 12 is provided as chuck assembly, and it inserts the outside in hole 38 It is fixed therein in end and by clasp 61.O 63 can be provided for close between hole 38 and locking hub system 12 Envelope.As best shown in the decomposition diagram of Fig. 2, pulse Vacuum hublock system 12 includes inner housing 60, and its storage departs from bullet Spring 62 is against its base portion 60A.Clutch ring 66 is positioned in outside against departing from spring 62.Clutch ring 66 includes that two rows are axial Spaced apart internal spline 66a, 66b(are as shown best in fig. 4) so as to be directed at external splines 58A, 58B selectivity on semiaxis 16 and Engage.Clutch ring 66 includes the external splines 66c that the internal spline 42 with wheel hub 18 engages.The outer surface of clutch ring 66 farther includes Multiple female axial groove 66d.Housing circle 68 engages with the outer shell body portion 60B of inner housing 60 and by clutch ring 66 and disengaging bullet Spring 62 is fixed in inner housing 60.Inner housing 60 includes multiple side stand 60C, and base portion 60A is connected to outside housing by it Part 60B is also incorporated in the female axial groove 66d of clutch ring 66, as best seen in figure 3.

Shell body 70 is attached to inner housing 60 and defines chamber 72 therein, as shown in Figure 4 and Figure 5.As in figure 2 it is shown, Housing circle 68 includes the recess 68a receiving side stand 60C.Shell body 70 includes engagement finger 70a being accommodated in groove 73, Groove 73 provides in the inner surface of the outer shell body portion 60B of inner housing 60.Shell body 70 can pass through engagement finger 70a It is rotationally locked to inner housing.Diaphragm 74 is placed in chamber 72 and has outer peripheral portion, and outer peripheral portion is captured on shell Between inner face and the housing circle 68 of the outward flange 70A of body 70.Main piston 76 is attached to the inside of diaphragm by spring arm parts 80 Projecting block 78.Spring arm parts 80 include the main part 82 with centre bore 84, and centre bore 84 is for receiving the prominent of diaphragm 74 Go out block 78.The main part 82 of spring arm parts 80 is accommodated in the cavity 86 in the lateral surface of main piston 76 and by tang 88 Being fixed therein, tang 88 is ultrasonically bonded to main part 82.A pair spring arm 80A, 80B extend from main part 82 and prolong Extend through the opening 76A in main piston 76.

Piston spring 90 and with one heart, less secondary spring 93 is placed between main piston 76 and auxiliary piston 92.Main piston 76 include annular sidewall 94, and it has the axially extended finger piece 96 from its circle spacing extended.Finger piece 96 is accommodated in In corresponding circumferential clearance 98 in the periphery of auxiliary piston 92.Auxiliary piston 92 include having a pair locking feature 100(such as Fig. 6 and Best shown in Fig. 7) newel 92A, locking feature 100 is for connecing spring arm 80A, 80B with this of spring arm parts 80 Close end 102 to engage, in order to auxiliary piston 92 is locked to main piston 76, and wherein piston spring 90 and secondary spring 93 are compressed in it Between.Locking feature 100 is engaged by abutting end 102 with the first settling position and return path.Specifically, Fig. 7 diagram relative to Locking feature 100 is in the abutting end 102 of the spring arm 80A of the various states of joint/disengaging.Illustrate that to be in first opened steady Determine the abutting end 102 of state, as by represented by position " U ".By the diaphragm 74 being applied to by vacuum pulse in chamber 72, make bullet Spring parts 80 and abutting end 102 engage with locking feature 100 at centre position " I ".Continuing along with engaging, abutting end 102 engages The ledge 104 of locking feature is to be fixed on main piston 76 and auxiliary piston 92 in second stable latched position " L ".Pass through Another pulse Vacuum is applied to diaphragm 74, main piston 76 is moved further to auxiliary piston 92 until the joint of spring arm 80A End 102 arrival off-position " R ", wherein the spring force of spring arm 80A pulls joint around the tip 106 of locking feature 100 End 102, so that when the vacuum is released, abutting end 102 is followed release way and opens to allow main piston from locking feature 100 76 move towards the direction away from auxiliary piston 92.When locking main piston 72 and auxiliary piston 78, depart from spring 62 and clutch ring 66 is pushed away To disengaging configuration, two row internal spline 66A, 66B are wherein made to depart from, such as Fig. 4 institute with two exclusive spline 58A, 58B on semiaxis 16 Show.When opening main piston 72 and auxiliary piston 78, under the bias force of piston spring 90 and secondary spring 93, opposing departs from spring The resistance of 62 moves clutch ring 66, so that two row internal spline 66A, 66B spline exclusive with two on semiaxis 16 58A, 58B connect Close, in order to by clutch ring 66, torque is delivered to wheel hub 18 from semiaxis 16, as shown in Figure 5.

Compact pulse Vacuum gyroaxis hublock 12 provides chuck design, in order to assemble.The multiple rows of of clutch ring 60 connects Multiple rows of external splines 58A, 58B of closing on tooth 66A, 66B and semiaxis 16 decrease the amount that clutch ring 66 moves axially.Utilize pulse true Empty joint method allows limited use vacuum, therefore allows the vacuum system of vehicle to have lower more resistance to than continuous vacuum hublock Sexual cycle for a long time.

The design of the present invention uses directly on semiaxis 16 rather than multiple rows of be commonly called on internal drive gear Engagement splines 58A, 58B, described internal drive gear will generally be mounted at above constant shaft 16, and wherein clutch ring 66 is interior with described Portion's travelling gear engages.In the design of the present invention, clutch ring 60 directly slides axially and directly inside wheel bearing hub 18 Constant shaft 16 engages, thus cancels internal drive gear and its support.This eliminates the need for friction source extra in system. It is internal to support constant shaft 16 that ball bearing 54 is arranged on wheel bearing hub 18.Then, constant shaft 16 is internal by hub bearing 22 Ball bearing 54 axially position, and also provide for the thrust loading of system.Needle bearing 44 on the inner side of constant shaft 16 provides The extra radial position of constant shaft 16.Knuckle vacuum seal 59 is between constant shaft 16 and knuckle 20.Therefore, should Sealing member 59 does not has relative motion during 4x2 operates, most to save fuel.

Present disclosure also uses two springs 90,93 for pulse Vacuum joint/detachment system.Big omnidistance spring 90 are used in the whole stroke of main piston 76, and main piston 76 is had the opposite effect by diaphragm 74.Omnidistance piston spring 90 is by clutch ring 66 It is fully engaged on constant shaft 16.Second secondary spring 93 is for by needing bigger vacuum to compress main piston 76 completely Help to reduce the whole stroke of main piston 76.Vacuum needed for the system of two springs allows sensitizing pulse/block sytem is bigger Separation.This allows bigger system tolerance, therefore makes it more sane, and allows less axially stacked size simultaneously.

The combination of present disclosure allows the axially stacked, so that the present invention's is designed to the most intensive envelope of minimum Dress.Whole chuck assembly 12 including housing assembly 60,70, clutch ring 66, diaphragm 74 and piston assembly 76,92 is placed in wheel rim The inner side of the opening 109 in the outer surface of 14, the opening 109 hole 111 in wheel rim 14 is opened.This allows for traditional automatic Outboard wheel end disconnects with the central lid in the hole 111 of the wheel being entirely encapsulated in the original equipment manufacturer being accommodated in traditional style After plate 110.The design of the present invention uses the system of pulse Vacuum startup to become and designs the most efficiently at present, and have The rotational resistance of minimum.

In order to the purpose of illustration and description have been provided for embodiment described above.It is not intended to exhaustive list Or the restriction disclosure.Each element of particular or feature are generally not limited to this particular, but, suitable It is interchangeable in the case of with, and can be used in selected embodiment, even if not being specifically shown or describing. Identical things can also be changed with various ways.These changes are not regarded as departure from present disclosure, and all these Amendment is intended to be included in the scope of the present disclosure.

Claims (22)

1., for wheel hub is joined to a pulse Vacuum hublock system for semiaxis, it comprises:

Housing assembly；

Clutch ring, it is placed in described housing assembly；

Departing from spring, it is placed between described housing assembly and described clutch ring；

Diaphragm, it is supported by described housing assembly；

Piston assembly, it engages with described diaphragm, and described piston assembly includes main piston and the auxiliary piston with interlock, institute State interlock for described main piston and described auxiliary piston being releasably engaged in latched position relative to each other；

Piston spring, it is placed between described main piston and described auxiliary piston；And

Secondary spring, it is placed between described main piston and described auxiliary piston.

2. pulse Vacuum hublock system as claimed in claim 1, wherein said piston spring is in the whole punching of described main piston Journey provides resistance, and described secondary spring only provides resistance during a part of stroke of described main piston.

3. pulse Vacuum hublock system as claimed in claim 2, wherein said auxiliary piston is placed against described clutch ring.

4. pulse Vacuum hublock system as claimed in claim 1, wherein said interlock includes being attached to described main work Filling in and have the spring arm parts of the first spring arm and the second spring arm, described first spring arm and described second spring arm are every The opposite side of the individual post being both mounted at described auxiliary piston and can be with on the apparent surface of the described post of described auxiliary piston One locking feature and the second locking feature engage.

5. pulse Vacuum hublock system as claimed in claim 4, wherein said housing assembly limits chuck assembly, and it supports Described clutch ring, diaphragm, main piston, auxiliary piston, spring arm parts, piston spring, secondary spring and disengaging spring, wherein said Chuck assembly is suitable to be accommodated in the hole of described wheel hub, and described clutch ring includes the outer flower that engages with the internal spline in described hole Key also includes a pair axially spaced inner spline housing, and described inner spline housing can move with axial with a pair on described semiaxis Spaced apart external splines socket merging is mobile to be disengaged with the external splines set axially spaced with a pair on described semiaxis.

6. pulse Vacuum hublock system as claimed in claim 4, wherein said spring arm parts include main part, and Described first spring arm and described second spring arm extend through the opening described main piston from described main part.

7. pulse Vacuum hublock system as claimed in claim 1, it is multiple that wherein said auxiliary piston includes in periphery surface Circumferential clearance, and described main piston includes multiple finger pieces of being accommodated in the described circumferential clearance of described auxiliary piston.

8. a pulse Vacuum hublock system, it comprises:

Wheel hub, it has internal spline；

Semiaxis, it has a pair axially spaced external splines set；

Chuck housing assembly, it is accommodated in the hole of described wheel hub；

Clutch ring, it is placed in described chuck housing assembly, and the described internal spline that described clutch ring has with described wheel hub connects The external splines closed, and a pair axially spaced-apart directly engaged with the described axially spaced external splines selectivity of described semiaxis The inner spline housing opened；

Diaphragm, it is supported by described chuck housing assembly；

Piston assembly, it is accommodated in described chuck housing assembly and engages with described diaphragm, and described piston assembly includes main work Plug and auxiliary piston, it has the spring being arranged there between, is used for making described main piston and described auxiliary piston in the opposite direction Biasing；And interlock, it is for being releasably engaged at lock relative to each other by described main piston and described auxiliary piston During location is put；The described chuck housing assembly within it with described clutch ring, described diaphragm and described piston assembly is accommodated in As integral type assembly in the described hole of described wheel hub.

9. pulse Vacuum hublock system as claimed in claim 8, wherein said chuck housing assembly includes inner housing and attached Receiving the shell body of described inner housing, described inner housing includes base portion and is connected to institute by multiple spaced apart side stands State the outer shell body portion of base portion.

10. pulse Vacuum hublock system as claimed in claim 9, wherein said clutch ring includes outer surface, and it includes receiving Receive multiple female axial grooves of the plurality of spaced apart side stand.

11. pulse Vacuum hublock systems as claimed in claim 8, it comprises the wheel rim being installed to described wheel hub further, Described wheel rim limits centre bore, and an opening is limited by the outer surface of described wheel rim, the most whole described chuck housing assembly The inner side of the described opening being placed in the described outer surface of described wheel rim.

12. pulse Vacuum hublock systems as claimed in claim 8, it comprises disengaging spring, described disengaging spring further It is placed between base portion and the described clutch ring of described chuck housing assembly.

13. pulse Vacuum hublock systems as claimed in claim 12, wherein said auxiliary piston is placed against described clutch Circle.

14. pulse Vacuum hublock systems as claimed in claim 8, wherein said interlock includes having the first spring arm Described auxiliary piston each it is placed in the spring arm parts of the second spring arm, described first spring arm and described second spring arm Post opposite side and with the first locking feature on the apparent surface of the described post of described auxiliary piston and the second locking feature Engage.

15. pulse Vacuum hublock systems as claimed in claim 14, wherein said spring arm parts include being attached to described The main part of main piston, and described first spring arm and described second spring arm extend through described from described main part Opening in main piston.

16. pulse Vacuum hublock systems as claimed in claim 8, it is multiple that wherein said auxiliary piston includes in periphery surface Circumferential clearance, and described main piston includes multiple finger pieces of being accommodated in the described circumferential clearance of described auxiliary piston.

17. 1 kinds of pulse Vacuum hublock systems, it comprises:

Wheel hub, it has internal spline；

Semiaxis, it has a pair axially spaced external splines set；

Housing assembly, it is accommodated in the hole in described wheel hub；

Clutch ring, it is placed in described housing assembly, and described clutch ring has what the described internal spline with described wheel hub engaged External splines, and a pair directly engaged with the described axially spaced external splines selectivity of described semiaxis is axially spaced Internal spline；

Diaphragm, it is supported by described housing assembly；

Piston assembly, it engages with described diaphragm, and described piston assembly includes main piston and auxiliary piston, and it has spring, described Spring is arranged there between for making described main piston and described auxiliary piston bias in the opposite direction；And interlock, It is for being releasably engaged at described main piston and described auxiliary piston in latched position relative to each other；And

Wheel rim, it is installed to described wheel hub, and described wheel rim limits centre bore, and an opening is limited by the outer surface of described wheel rim Fixed, the most whole described housing assembly, clutch ring, diaphragm and piston assembly are placed in the described outer surface of described wheel rim The inner side of described opening.

18. pulse Vacuum hublock systems as claimed in claim 17, it comprises disengaging spring, described disengaging spring further It is placed between the base portion of described housing assembly and described clutch ring.

19. pulse Vacuum hublock systems as claimed in claim 17, wherein said auxiliary piston is placed against described clutch Circle.

20. pulse Vacuum hublock systems as claimed in claim 17, wherein said housing assembly limits chuck assembly, its Supportting described clutch ring, diaphragm, main piston, auxiliary piston and described interlock, wherein said chuck assembly is accommodated in described wheel hub Hole in.

21. pulse Vacuum hublock systems as claimed in claim 17, wherein said auxiliary piston includes in periphery surface many Individual circumferential clearance, and described main piston includes multiple finger pieces of being accommodated in the described circumferential clearance of described auxiliary piston.

22. pulse Vacuum hublock systems as claimed in claim 17, it comprises further and is placed in described main piston and institute State the piston spring between auxiliary piston, and be placed in the secondary spring between described main piston and described auxiliary piston, described work Plug spring provides resistance in the whole stroke of described main piston, and described secondary spring is only in the part punching of described main piston Resistance is provided during journey.